3.3.2.1 Simulation model
The simulations are carried out using the ANANAS code
(Team, 2013) developed by LEMMA, which solves the
incompressible Navier-Stokes equations. Given the velocities
considered and the characteristic dimension of
the problem (the height of the obstacle), the Reynolds
numbers that are at stake correspond to fully turbulent
flows. As a consequence, beside the mass and momentum
equations, the code also solves the two equations of
the k-ε turbulence model (Launder & Spalding, 1974) in
order to take into account turbulence. In addition, a law
for the wall is applied to account for the non-slip condition
at the wall. However, regarding the particle-skirt interaction,
a friction coefficient (Cf) between 0.04 and 0.1
is considered. The algorithm used for space integration is
of third order accuracy.
Computat ional modeling: Boundar y conditions
The computational domain is a rectangular box of dimensions
[-20 m, 60 m] x [0 m, -40 m] in the XY plane with Y being
the depth, and the center of the domain being located
at the center of the buoyant body. These dimensions were
chosen to allow the flow to be fully established, but at the
same time to assure that the inlet and outlet boundaries
would not be so close as to influence it. Indeed, downstream
of the skirt, it is important that the computational
domain is long enough for the flow to reattach before the
outlet section.